Unify settings parsing

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -400,7 +400,7 @@ private sealed trait YSettings:
   val YstopBefore: Setting[List[String]] = PhasesSetting(ForkSetting, "Ystop-before", "Stop before") // stop before erasure as long as we have not debugged it fully
   val YshowSuppressedErrors: Setting[Boolean] = BooleanSetting(ForkSetting, "Yshow-suppressed-errors", "Also show follow-on errors and warnings that are normally suppressed.")
   val YdetailedStats: Setting[Boolean] = BooleanSetting(ForkSetting, "Ydetailed-stats", "Show detailed internal compiler stats (needs Stats.enabled to be set to true).")
-  val YkindProjector: Setting[String] = ChoiceSetting(ForkSetting, "Ykind-projector", "[underscores, disable]", "Allow `*` as type lambda placeholder to be compatible with kind projector. When invoked as -Ykind-projector:underscores will repurpose `_` to be a type parameter placeholder, this will disable usage of underscore as a wildcard.", List("disable", "", "underscores"), "disable")
+  val YkindProjector: Setting[String] = ChoiceSetting(ForkSetting, "Ykind-projector", "[underscores, enable, disable]", "Allow `*` as type lambda placeholder to be compatible with kind projector. When invoked as -Ykind-projector:underscores will repurpose `_` to be a type parameter placeholder, this will disable usage of underscore as a wildcard.", List("disable", "enable", "underscores"), "disable")
   val YprintPos: Setting[Boolean] = BooleanSetting(ForkSetting, "Yprint-pos", "Show tree positions.")
   val YprintPosSyms: Setting[Boolean] = BooleanSetting(ForkSetting, "Yprint-pos-syms", "Show symbol definitions positions.")
   val YnoDeepSubtypes: Setting[Boolean] = BooleanSetting(ForkSetting, "Yno-deep-subtypes", "Throw an exception on deep subtyping call stacks.")

compiler/src/dotty/tools/dotc/config/Settings.scala

@@ -72,9 +72,10 @@ object Settings:
     ignoreInvalidArgs: Boolean = false,
     propertyClass: Option[Class[?]] = None,
     deprecationMsg: Option[String] = None)(private[Settings] val idx: Int) {
-
+
+
     assert(name.startsWith(s"-$category"), s"Setting $name does not start with category -$category")
-
+    assert(!choices.contains(""), s"Empty string is not supported as a choice for setting $name")
     // Without the following assertion, it would be easy to mistakenly try to pass a file to a setting that ignores invalid args.
     // Example: -opt Main.scala would be interpreted as -opt:Main.scala, and the source file would be ignored.
     assert(!(summon[ClassTag[T]] == ListTag && ignoreInvalidArgs), s"Ignoring invalid args is not supported for multivalue settings: $name")
@@ -165,6 +166,12 @@ object Settings:
           val output = if (isJar) JarArchive.create(path) else new PlainDirectory(path)
           update(output, args)
         }
+
+      def setVersion(argValue: String, args: List[String]) =
+        ScalaVersion.parse(argValue) match {
+          case Success(v) => update(v, args)
+          case Failure(ex) => fail(ex.getMessage, args)
+        }
 
       def appendList(strings: List[String], args: List[String]) =
         choices match
@@ -180,38 +187,31 @@ object Settings:
             setBoolean(argRest, args)
           case (OptionTag, _) =>
             update(Some(propertyClass.get.getConstructor().newInstance()), args)
-          case (ListTag, args) if argRest.nonEmpty =>
-            val strings = argRest.split(",").toList
-            appendList(strings, args)
-          case (ListTag, arg2 :: args2) if !(arg2 startsWith "-")=>
-            appendList(arg2 :: Nil, args2)
-          case (StringTag, _) if argRest.nonEmpty || choices.exists(_.contains("")) =>
-            setString(argRest, args)
-          case (StringTag, arg2 :: args2) =>
-            if (arg2 startsWith "-") missingArg
-            else setString(arg2, args2)
-          case (OutputTag, args) if argRest.nonEmpty =>
-            setOutput(argRest, args)
-          case (OutputTag, arg2 :: args2) =>
-            setOutput(arg2, args2)
-          case (IntTag, args) if argRest.nonEmpty =>
-            setInt(argRest, args)
-          case (IntTag, arg2 :: args2) =>
-            setInt(arg2, args2)
-          case (VersionTag, _) if argRest.nonEmpty =>
-            ScalaVersion.parse(argRest) match {
-              case Success(v) => update(v, args)
-              case Failure(ex) => fail(ex.getMessage, args)
-            }
-          case (VersionTag, arg2 :: args2) =>
-            ScalaVersion.parse(arg2) match {
-              case Success(v) => update(v, args2)
-              case Failure(ex) => fail(ex.getMessage, args2)
-            }
-          case (_, Nil) =>
-            missingArg
+          case (_, args) =>
+            val argInArgRest = !argRest.isEmpty
+            val argAfterParam = !argInArgRest && args.nonEmpty && !args.head.startsWith("-")
+            if argInArgRest then
+              doSetArg(argRest, args)
+            else if argAfterParam then
+              doSetArg(args.head, args.tail)
+            else missingArg
         }
 
+      def doSetArg(arg: String, argsLeft: List[String]) = summon[ClassTag[T]] match
+          case ListTag =>
+            val strings = arg.split(",").toList
+            appendList(strings, argsLeft)
+          case StringTag =>
+            setString(arg, argsLeft)
+          case OutputTag =>
+            setOutput(arg, argsLeft)
+          case IntTag =>
+            setInt(arg, argsLeft)
+          case VersionTag =>
+            setVersion(arg, argsLeft)
+          case _ =>
+            missingArg
+
       def matches(argName: String): Boolean = 
         (allFullNames).exists(_ == argName.takeWhile(_ != ':')) || prefix.exists(arg.startsWith)
 

tests/neg/kind-projector.scala

@@ -1,4 +1,4 @@
-//> using options -Ykind-projector
+//> using options -Ykind-projector:enable
 
 package kind_projector_neg
 

tests/pos-with-compiler-cc/dotc/config/ScalaSettings.scala

@@ -289,7 +289,7 @@ private sealed trait YSettings:
   val YstopBefore: Setting[List[String]] = PhasesSetting("-Ystop-before", "Stop before") // stop before erasure as long as we have not debugged it fully
   val YshowSuppressedErrors: Setting[Boolean] = BooleanSetting("-Yshow-suppressed-errors", "Also show follow-on errors and warnings that are normally suppressed.")
   val YdetailedStats: Setting[Boolean] = BooleanSetting("-Ydetailed-stats", "Show detailed internal compiler stats (needs Stats.enabled to be set to true).")
-  val YkindProjector: Setting[String] = ChoiceSetting("-Ykind-projector", "[underscores, disable]", "Allow `*` as type lambda placeholder to be compatible with kind projector. When invoked as -Ykind-projector:underscores will repurpose `_` to be a type parameter placeholder, this will disable usage of underscore as a wildcard.", List("disable", "", "underscores"), "disable")
+  val YkindProjector: Setting[String] = ChoiceSetting("-Ykind-projector", "[underscores, enable, disable]", "Allow `*` as type lambda placeholder to be compatible with kind projector. When invoked as -Ykind-projector:underscores will repurpose `_` to be a type parameter placeholder, this will disable usage of underscore as a wildcard.", List("disable", "enable", "underscores"), "disable")
   val YprintPos: Setting[Boolean] = BooleanSetting("-Yprint-pos", "Show tree positions.")
   val YprintPosSyms: Setting[Boolean] = BooleanSetting("-Yprint-pos-syms", "Show symbol definitions positions.")
   val YnoDeepSubtypes: Setting[Boolean] = BooleanSetting("-Yno-deep-subtypes", "Throw an exception on deep subtyping call stacks.")

tests/pos/kind-projector.scala

@@ -1,4 +1,4 @@
-//> using options -Ykind-projector
+//> using options -Ykind-projector:enable
 
 package kind_projector